Device, system, and method for qubit calibration, measurement and control

ABSTRACT

The present disclosure relates to a qubit calibration device and a qubit measurement and control method. The qubit calibration device includes a qubit processing unit including circuitry configured to, after receiving a qubit control signal, process one or more qubits; and an adjustable device configured to, after receiving the qubit control signal, generate a detection signal used to further adjust the qubit control signal, wherein the qubit processing unit and the adjustable device are disposed on a same substrate.

CROSS REFERENCE TO RELATED APPLICATION

The present disclosure claims the benefit of and is a divisional of U.S.application Ser. No. 16/779,337, filed on Jan. 31, 2020, which claimsthe benefit of priority to Chinese application number 201910107886.2,filed Feb. 2, 2019, both of which are incorporated herein by referencein their entireties.

BACKGROUND

Quantum computing and quantum information are based on principles ofquantum mechanics to perform computing and information processing.Quantum computing is an interdisciplinary subject that is closelyrelated to multiple disciplines such as quantum physics, computerscience, information science, etc. In the last two decades, quantumcomputing has developed rapidly. Quantum algorithms running on quantumcomputers have been applied in various fields, such as factorization,and unstructured search, and have demonstrated far more superiorperformance compared to classical algorithms performed on classicalcomputers. As a result, quantum computing is expected to exceed theperformance of conventional computing. But quantum computing requirescalibration, measurement, and control to maintain precision of theinformation unit (e.g., qubits), which sometimes can be challenging.

SUMMARY OF THE DISCLOSURE

The present disclosure provides a qubit measurement and control system,comprising: a qubit processing unit including circuitry configured toprocess one or more qubits; an adjustable device disposed adjacent tothe qubit processing unit, the adjustable device and the qubitprocessing unit being within a same environment; and a control signalgenerator selectively connected to the qubit processing unit and theadjustable device, the control signal generator being configured togenerate a qubit control signal to be selectively transmitted to thequbit processing unit and the adjustable device.

According to some embodiments of the disclosure, the one or more qubitsare based on a superconducting Josephson junction.

According to some embodiments of the disclosure, the qubit measurementand control system further includes a first mode selection devicedisposed on a first side of the qubit processing unit and the adjustabledevice, the first side being a side where the control signal generatoris located.

According to some embodiments of the disclosure, the qubit measurementand control system further includes a second mode selection devicedisposed on a second side of the qubit processing unit and theadjustable device.

According to some embodiments of the disclosure, the qubit processingunit and the adjustable device are disposed on a same chip.

According to some embodiments of the disclosure, the qubit processingunit and the adjustable device are disposed on a same printed circuitboard (PCB).

According to some embodiments of the disclosure, the qubit processingunit, the adjustable device, the first mode selection device and thesecond mode selection device are disposed on the same chip.

According to some embodiments of the disclosure, the qubit processingunit, the adjustable device, the first mode selection device and thesecond mode selection device are disposed on the same printed circuitboard (PCB).

According to some embodiments of the disclosure, the qubit measurementand control system further includes at least one regulator disposedbetween the control signal generator and the qubit processing unit.

According to some embodiments of the disclosure, the qubit controlsignal includes a microwave signal or a laser signal.

According to some embodiments of the disclosure, the adjustable devicereceives the qubit control signal and generates a detection signal, thedetection signal is fed back a control device, and the control devicecontrols, at least according to the detection signal, the control signalgenerator to adjust the qubit control signal.

According to some embodiments of the disclosure, adjusting the qubitcontrol signal by the control signal generator includes adjusting atleast one of the parameters including phase, intensity, and frequency.

According to some embodiments of the disclosure, the first modeselection device and the second mode selection device are configured toimplement: a plurality of control signal mode selections and controlsignal path selections respectively.

According to some embodiments of the disclosure, the control signal pathmode selections include a reflection mode and a through mode.

According to some embodiments of the disclosure, the qubit processingunit and the adjustable device (e.g., on the chip or PCB) are disposedin a low-temperature environment, the low-temperature environmentincluding a liquid helium temperature zone.

According to some embodiments of the disclosure, a qubit calibrationdevice is provided, which includes: a qubit processing unit includingcircuitry configured to, after receiving a qubit control signal, processone or more qubits; and an adjustable device configured to, afterreceiving the qubit control signal, generate a detection signal used tofurther adjust the qubit control signal, the qubit processing unit andthe adjustable device being disposed on a same substrate (e.g., a singlechip or a PCB).

According to some embodiments, the one or more qubits are based on asuperconducting Josephson junction.

According to some embodiments, the qubit calibration device furthercomprises: a first mode selection device located on one side of thequbit processing unit and disposed on the same substrate.

According to some embodiments, the qubit calibration device furthercomprises: a second mode selection device located on the other side ofthe qubit processing unit from the first mode selection device, and thesecond mode selection device being disposed on the same substrate.

According to some embodiments, the qubit control signal comprises amicrowave signal or a laser signal.

According to some embodiments, the qubit control signal is adjusted byat least one of the parameters including phase, intensity, andfrequency.

According to some embodiments, the substrate is disposed in alow-temperature environment comprising a liquid helium temperature zone.

According to some embodiments, the substrate is a single chip or aprinted circuit board (PCB).

According to some embodiments, a qubit measurement and control method isprovided, which includes: receiving a qubit control signal at anadjustable device; detecting, by the adjustable device, the qubitcontrol signal, to obtain a detection signal, wherein the qubit controlsignal is adjusted based on a comparison between the detection signaland the qubit control signal.

According to some embodiments, the qubit control signal comprises amicrowave signal or a laser signal.

According to some embodiments, the qubit control signal is adjusted byat least one of the following parameters: phase, intensity, andfrequency.

According to some embodiments, the detection signal is transmitted to acontrol device via a reflection mode or a through mode.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described herein are provided to provide a furtherunderstanding of the disclosure and constitute a part of the disclosure.The exemplary embodiments of the disclosure and description thereof areused to explain the disclosure, and do not constitute improperlimitations to the disclosure. In the drawings:

FIG. 1 is a schematic diagram of an example qubit measurement andcontrol system, according to some embodiments of the present disclosure.

FIG. 2 is a schematic diagram of an example qubit calibration device,according to some embodiments of the present disclosure.

FIG. 3 is a schematic diagram of an example qubit calibration device,according to some embodiments of the present disclosure.

FIG. 4 is a schematic diagram of an example qubit calibration device,according to some embodiments of the present disclosure.

FIG. 5 is a schematic diagram of an example qubit calibration device,according to some embodiments of the present disclosure.

FIG. 6 is a schematic diagram of an example qubit calibration device,according to some embodiments of the present disclosure.

FIG. 7 is a schematic diagram of an example qubit calibration device,according to some embodiments of the present disclosure.

FIG. 8 is a schematic diagram of an example qubit calibration device,according to some embodiments of the present disclosure.

FIG. 9 is a schematic diagram of an example qubit calibration device,according to some embodiments of the present disclosure.

FIG. 10 is a schematic diagram of an example qubit measurement andcontrol system, according to some embodiments of the present disclosure.

FIG. 11 is a flowchart of an example qubit measurement and controlmethod, according to some embodiments of the present disclosure.

DETAILED DESCRIPTION

When reading in conjunction with the drawings, the foregoing summary andthe following detailed description of certain embodiments will be betterunderstood. The schematic diagrams of functional blocks of someembodiments in the figures do not necessarily indicate the divisionbetween hardware circuits. Thus, for example, one or more of thefunctional blocks (e.g., a processor or a memory) may be implemented ina single piece of hardware (e.g., a signal processor or a random accessmemory, a hard disk, etc.) or a plurality of pieces of hardware.Similarly, the program may be a stand-alone program, may be combinedinto a routine in an operating system, or may be a function in aninstalled software package, etc. It should be understood that someembodiments are not limited to the arrangements and tools shown in thefigures.

As used in the disclosure, the elements or steps described in a singularform or starting with “a” or “an” should be construed as that the pluralof the elements or steps are not excluded unless such exclusion isexplicitly stated. In addition, references to “one embodiment” are notintended to be construed as excluding the existence of additionalembodiments that also incorporate the described features. Embodimentsthat “include,” “comprise” or “have” an element or a plurality ofelements having a particular attribute may include additional suchelements that do not have that attribute, unless the contrary isexplicitly stated.

One of the basic characteristics of a quantum computer is that theadopted information unit is not a classical binary bit, but a qubit(e.g., also referred to as a quantum bit, or a qbit). In someembodiments, qubits may include particles like electrons, or otherquasi-particles in elementary excitation. For example, with regard toelectrons, a spin-up state (e.g., electron spins clockwise on its axis)may represent 1, and in a spin-down state (e.g., electron spinscounter-clockwise on its axis) may represent 0. Further, a quantum statewith spins both up and down is called a superposition state. A smallnumber of particles in the superposition state may carry a large amountof information. For example, 100 particles in the superposition statemay represent 1 to 2100 digits. Accordingly, quantum computer may usemicrowave, laser pulses, or other suitable methods to manipulate (e.g.,excite) particles to perform operations and computations with qubits.

At present, implementations of qubits in quantum computing can be basedon superconducting Josephson junctions, ion traps, magnetic resonance,topological quantum, etc. Further, one of the common and majorimplementations of qubits includes superconducting quantum computingbased on Josephson junctions. A superconducting qubit chip needs to bekept in a low-temperature environment (e.g., typically a temperaturezone to keep liquid helium) to maintain the superconductivity, and thelow-temperature environment is usually provided by a dilutionrefrigerator. In some embodiments, an input control signal istransmitted to a superconducting qubit chip through a coaxial cable.However, as shown in FIG. 1 , the input process may take a longdistance, which may span a large temperature range. In addition, theremay include a number of filters, attenuators, or adapters. Theserelatively complex environments, especially the low-temperatureenvironment, may have a large impact on the control signal, which mayfurther cause the control signal inputted into the superconducting qubitchip to be significantly different from expected. As a result, a precisecontrol over the superconducting qubit may be limited, further makingthe actual implementations of the quantum computers more difficult.

The present disclosure overcomes these issues by providing a calibrationdevice and a corresponding calibration method that support measurementand control of a qubit chip for improved precision.

FIG. 2 illustrates a schematic diagram of an example qubit calibrationdevice 200, according to some embodiments of the present disclosure. Insome embodiments, a qubit processing unit 22 and an adjustable device 23are disposed on a single chip 25. Single chip 25 may include a singlewafer that is processed to provide qubit processing unit 22 andadjustable device 23.

In some embodiments, qubit processing unit 22 and adjustable device 23are placed as close as possible so that they are placed in the sameenvironment (e.g., within the same temperature range).

In some embodiments, qubit processing unit 22 includes a chip (or a unitmodule on a chip) including one or more qubits. For example, qubitprocessing unit 22 may include: a qubit (e.g., a smallquantum-mechanical system), a resonator, circuitry configured to receivean input signal (e.g., input signal 21, may also be referred to as aqubit control signal) on the chip, and corresponding circuitryconfigured to amplify and output a qubit signal on the chip. Qubitprocessing unit 22 is configured to transform the quantum states of oneor more qubits after receiving input signal 21. The output qubit signalsare obtained by performing measurement on the qubits. Qubit processingunit 22 may be a quantum computing processor, or may be a modularquantum computing chip that includes a plurality of modules with onecorresponding to a quantum computing processor. In some embodiments,adjustable device 23 includes a controllable switch and a plurality ofstandard devices for calibration. In some embodiments, the standarddevices for calibration use standards such as Open\Short\FixedLoad\Thru, and input signal 21 may be calibrated based on thesedifferent standards.

In some embodiments, input signal 21 is transmitted using a coaxialcable. Input signal 21 may include a signal for controlling a qubit andmay be generated by a control signal generator. For example, inputsignal 21 may include a microwave signal or a laser signal. Thoseskilled in the art can select any suitable control signal generator andselect parameters, such as phase, intensity, and frequency, of inputsignal 21 according to the desired control over the qubit. The selectedparameters may be simultaneously transmitted to a control device (e.g.,may be control signal generator 105, a module of control signalgenerator 105, or control device 103 communicatively coupled to controlsignal generator 105, FIG. 10 ) for controlling (e.g., analyzing oradjusting) input signal 21 to provide more precise control of the qubit.

In some embodiments, the qubit is based on a superconducting Josephsonjunction.

In some embodiments, single chip 25 is placed in a low-temperatureenvironment in use. The low-temperature environment may include atemperature range from 100 mK to 4.2 K (K refers to Kelvin). Thelow-temperature environment may be provided by, for example, but is notlimited to, a dilution refrigerator. In some embodiments, input signal21 may be distorted when transmitted from a room temperature environment(or a relatively high-temperature region) to the low-temperatureenvironment. For example, the parameters, such as phase, intensity andfrequency, of input signal 21 may change. As a result, when input signal21 is transmitted to qubit processing unit 22, the actual phase,intensity, frequency and other parameters will deviate from thecorresponding preset values, thereby making the control process over thequbit more difficult, less accurate, or even uncontrollable.

In some embodiments, after arriving at chip 25, input signal 21 may betransmitted to qubit processing unit 22 to control the qubit, or may betransmitted to adjustable device 23 for calibration. Those skilled inthe art will appreciate that selection of transmission of input signal21 to qubit processing unit 22 or adjustable device 23 may be made by,for example, but not limited to, an automatic switching device prior toreceiving input signal 21 for calibration of the qubit (e.g., atadjustable device 23) or control over the qubit (e.g., at qubitprocessing unit 22). When input signal 21 is transmitted to adjustabledevice 23, a detection signal 24 is obtained (e.g., from adjustabledevice 23). Since qubit processing unit 22 and adjustable device 23 areplaced close to each other (e.g., in the same environment), input signal21 arrived at adjustable device 23 may be substantially similar oridentical to input signal 21 arrived at qubit processing unit 22.

In some embodiments, detection signal 24 is further fed back to thecontrol device (e.g., control signal generator 105 of FIG. 10 , toprovide information used to control or adjust input signal 21transmitted to qubit processing unit 22 on chip 25 for more precisecontrol of qubit). A feedback path of detection signal 24 may includedifferent modes such as transmission “through,” or via “reflection,” ora combination thereof. In some embodiments, the control device obtains adegree of deviation between the signal actually arriving at adjustabledevice 23 and input signal 21 according to comparison between parametersof detection signal 24 and initial parameters of input signal 21. Theobtained degree of deviation may be used to make correspondingadjustment to input signal 21 generated by the control signal generator(e.g., control signal generator 105, FIG. 10 ). In some examples, theadjustment may include adjustment to any one or more of theabove-mentioned parameters, such as phase, intensity or frequency.

In some embodiments, the above process may be repeated multiple timesuntil the degree of deviation reaches a preset range of convergence. Insome examples, the preset range of convergence may include that adeviation between any parameter, e.g., phase, intensity or frequency, ofdetection signal 24 and the corresponding parameter of input signal 21is less than a preset value. In some other examples, the preset range ofconvergence may include that the deviation of each of phase, intensity,and frequency between detection signal 24 and input signal 21 is lessthan a preset value. In yet some other examples, the preset range ofconvergence may include that the deviation between one or more setfunction values of phase, intensity, and frequency of detection signal24 and the corresponding set function values of input signal 21 is lessthan a preset value.

A relationship between the degree of deviation and the adjustment neededcan be obtained by theoretical calculation, or by an empiricalcorrespondence obtained according to an actual use environment, orthrough a combination thereof.

In some embodiments, through the above setting, input signal 21 finallyarrived at qubit processing unit 22 may satisfy preset parameter values(e.g., including phase, intensity, or frequency, etc.), so that thequbit can be more precisely controlled.

FIG. 3 illustrates a schematic diagram of an example qubit calibrationdevice 300, according to some embodiments of the present disclosure. Insome embodiments, a qubit processing unit 32 and an adjustable device 33are disposed on a single printed circuit board (PCB) 35. The framestructure as illustrated in FIG. 3 may be simpler for the fabricationprocess than the structure illustrated in FIG. 2 .

In some embodiments, qubit processing unit 32 and adjustable device 33are placed as close as possible so that they are placed in the sameenvironment (e.g., within the same temperature range).

In some embodiments, qubit processing unit 32 includes a PCB (or a unitmodule on a PCB) including one or more qubits. For example, qubitprocessing unit 32 and may include: a qubit (e.g., a smallquantum-mechanical system), a resonator, circuitry configured to receivean input signal (e.g., input signal 31, may also be referred to as aqubit control signal), and corresponding circuitry configured to amplifyand output a signal. In some embodiments, adjustable device 33 includesa controllable switch and a plurality of standard devices forcalibration. In some embodiments, the standard devices for calibrationuse standards such as Open\Short\Fixed Load\Thru, and input signal 21may be calibrated based on these different standards.

In some embodiments, input signal 31 is transmitted using a coaxialcable. Input signal 31 may include a signal for controlling a qubit andmay be generated by a control signal generator. For example, inputsignal 31 may include a microwave signal or a laser signal. Thoseskilled in the art can select any suitable signal generator and selectparameters, such as phase, intensity, and frequency, of input signal 31according to the desired control over the qubit. The selected parametersmay be simultaneously transmitted to a control device (e.g., may becontrol signal generator 105, a module of control signal generator 105,or control device 103 communicatively coupled to control signalgenerator 105, FIG. 10 ) for controlling (e.g., adjusting) input signal31 to provide more precise control of the qubit.

In some embodiments, the qubit is based on a superconducting Josephsonjunction.

In some embodiments, single PCB 35 is placed in a low-temperatureenvironment in use. the low-temperature environment may include atemperature range from 100 mK to 4.2 K (K refers to Kelvin). Thelow-temperature environment may be provided by, for example, but is notlimited to, a dilution refrigerator. In some embodiments, input signal31 may be distorted when transmitted from a room temperature environment(or a relatively high-temperature region) to the low-temperatureenvironment. For example, the parameters, such as phase, intensity andfrequency, of input signal 31 may change. As a result, when input signal31 is transmitted to qubit processing unit 32, the actual phase,intensity, frequency and other parameters will deviate from thecorresponding preset values, thereby making the control process over thequbit more difficult, less accurate, or even uncontrollable.

In some embodiments, after arrived at PCB 35, input signal 31 may betransmitted to qubit processing unit 32 to control the qubit, or may betransmitted to adjustable device 33 for calibration. Those skilled inthe art will appreciate that selection of transmission of input signal31 to qubit processing unit 32 or adjustable device 33 may be made by,for example, but not limited to, an automatic switching device prior toreceiving input signal 31 for calibration of the qubit (e.g., atadjustable device 33) or control over the qubit (e.g., at qubitprocessing unit 32). When input signal 31 is transmitted to adjustabledevice 33, a detection signal 34 is obtained (e.g., from adjustabledevice 33). Since qubit processing unit 32 and adjustable device 33 areplaced close to each other (e.g., in the same environment), input signal31 arrived at adjustable device 33 may be substantially similar oridentical to input signal 31 arriving at qubit processing unit 32.

In some embodiments, detection signal 34 is further fed back to thecontrol device (e.g., control signal generator 105 of FIG. 10 to provideinformation used to control or adjust input signal 31 transmitted toqubit processing unit 32 on PCB 35 for more precise control of qubit). Afeedback path of detection signal 34 may include transmission “through,”or via “reflection,” or a combination thereof. In some embodiments, thecontrol device obtains a degree of deviation between the signal actuallyarrived at adjustable device 33 and input signal 31 according tocomparison between parameters of detection signal 34 and initialparameters of input signal 31. The obtained degree of deviation may beused to make corresponding adjustment to input signal 31 generated bythe control signal generator (e.g., control signal generator 105, FIG.10 ). In some examples, the adjustment may include adjustment to any oneor more of the above-mentioned parameters, such as phase, intensity orfrequency.

In some embodiments, the above process may be repeated multiple timesuntil the degree of deviation reaches a preset range of convergence. Insome examples, the preset range of convergence may include that adeviation between any parameter, e.g., phase, intensity, or frequency,of detection signal 34 and the corresponding parameter of input signal31 is less than a preset value. In some other examples, the preset rangeof convergence may include that the deviation of each of phase,intensity and frequency between detection signal 34 and input signal 31is less than a preset value. In yet some other examples, the presetrange of convergence may include that the deviation between one or moreset function values of phase, intensity and frequency of detectionsignal 34 and the corresponding set function values of input signal 31is less than a preset value.

A relationship between the degree of deviation and the adjustment neededcan be obtained by theoretical calculation, or by an empiricalcorrespondence obtained according to an actual use environment, orthrough a combination thereof.

In some embodiments, through the above setting, input signal 31 finallyarrived at qubit processing unit 32 may satisfy preset parameter values(e.g., including phase, intensity, or frequency, etc.), so that thequbit can be more precisely controlled.

FIG. 4 illustrates a schematic diagram of an example qubit calibrationdevice 400, according to some embodiments of the present disclosure. Insome embodiments, a qubit processing unit 42 and an adjustable device 43are disposed on a single chip 45. Single chip 45 may include a singlewafer that is processed to provide qubit processing unit 42 andadjustable device 43. In some embodiments, qubit calibration device 400further includes a mode selection device 46. Mode selection device 46may change a path of an input signal 41 via remote controlling (e.g.,based on, but not limited to, electrical signals). In some examples, ifa mode of transmitting input signal 41 to qubit processing unit 42 isselected, the qubit is controlled. In some other examples, if a mode oftransmitting input signal 41 to adjustable device 43 is selected,calibration (e.g., of input signal 41) may be performed. In someembodiments, mode selection device 46 is disposed at input signal 41side (e.g., prior to input signal 41 arriving at qubit processing unit42 or adjustable device 43 on single chip 45).

In some embodiments, qubit processing unit 42 and adjustable device 43are placed as close as possible so that they are placed in the sameenvironment (e.g., within the same temperature range). In someembodiments, the electrical wires and circuitry connecting modeselection device 46 and qubit processing unit 42 have substantiallysimilar microwave-responsive characteristics as the electrical wires andcircuitry between mode selection device 46 and adjustable device 43.

In some embodiments, qubit processing unit 42 includes a chip (or a unitmodule on a chip) including one or more qubits. For example, qubitprocessing unit 22 may include: a qubit (e.g., a smallquantum-mechanical system), a resonator, circuitry configured to receivean input signal (e.g., input signal 41, may also be referred to as aqubit control signal), and corresponding circuitry configured to amplifyand output a signal. In some embodiments, adjustable device 43 includesa controllable switch and a plurality of standard devices forcalibration. In some embodiments, the standard devices for calibrationuse standards such as Open\Short\Fixed Load\Thru, and input signal 41may be calibrated based on these different standards. In someembodiments as discussed in the present disclosure, by performingcalibration at adjustable device 43, a to-be-controlled qubit signal(e.g., qubit signal 111 controlled and adjusted by qubit signalgenerator 105 in view of feedback information detected from detectionsignal as discussed with reference to FIG. 10 ) arrived at qubitprocessing unit 42 can better meet the requirements.

In some embodiments, input signal 41 is transmitted using a coaxialcable. Input signal 41 may include a signal for controlling a qubit andmay be generated by a control signal generator. For example, inputsignal 41 may include a microwave signal or a laser signal. Thoseskilled in the art can select any suitable signal generator and selectparameters, such as phase, intensity, and frequency, of input signal 41according to the desired control over the qubit. The selected parametersmay be simultaneously transmitted to a control device (e.g., may becontrol signal generator 105, a module of control signal generator 105,or control device 103 communicatively coupled to control signalgenerator 105, or control device 103, FIG. 10 ) for controlling (e.g.,adjusting) input signal 41 to provide more precise control of the qubit.

In some embodiments, the qubit is based on a superconducting Josephsonjunction.

In some embodiments, single chip 45 is placed in a low-temperatureenvironment in use. The low-temperature environment may include atemperature range from 100 mK to 4.2 K (K refers to Kelvin). Thelow-temperature environment may be provided by, for example, but is notlimited to, a dilution refrigerator. In some embodiments, input signal41 may be distorted when transmitted from a room temperature environment(or a relatively high-temperature region) to the low-temperatureenvironment. For example, the parameters, such as phase, intensity, andfrequency, of input signal 41 may change. As a result, when input signal41 is transmitted to qubit processing unit 42, the actual phase,intensity, frequency and other parameters will deviate from thecorresponding preset values, thereby making the control process over thequbit more difficult, less accurate, or even uncontrollable.

In some embodiments, input signal 41 may be inputted to qubit processingunit 42 via mode selection device 46 to control the qubit or may beinputted to adjustable device 43 for calibration. When input signal 41is inputted to adjustable device 43, a detection signal 44 is obtained.Since qubit processing unit 42 and adjustable device 43 are placed closeto each other (e.g., in the same environment), input signal 41 arrivedat adjustable device 43 may be substantially similar or identical toinput signal 41 arrived at qubit processing unit 42.

In some embodiments, detection signal 44 is further fed back to thecontrol device (e.g., control signal generator 105 of FIG. 10 , toprovide information used to control or adjust input signal 41transmitted to qubit processing unit 42 on chip 45 for more precisecontrol of qubit). A feedback path of detection signal 44 may includetransmission “through,” or via “reflection,” or a combination thereof.In some embodiments, the control device obtains a degree of deviationbetween the signal actually arrived at adjustable device 43 and inputsignal 41 according to comparison between parameters of detection signal44 and initial parameters of input signal 41. The obtained degree ofdeviation may be used to make corresponding adjustment to input signal41 generated by the control signal generator (e.g., control signalgenerator 105, FIG. 10 ). In some examples, the adjustment may includeadjustment to any one or more of the above-mentioned parameters, such asphase, intensity, or frequency.

In some embodiments, the above process may be repeated multiple timesuntil the degree of deviation reaches a preset range of convergence. Insome examples, the preset range of convergence may include that adeviation between any parameter, e.g., phase, intensity, or frequency,of detection signal 44 and the corresponding parameter of input signal41 is less than a preset value. In some other examples, the preset rangeof convergence may include that the deviation of each of phase,intensity, and frequency between detection signal 44 and input signal 41is less than a preset value. In yet some other examples, the presetrange of convergence may include that the deviation between one or moreset function values of phase, intensity, and frequency of detectionsignal 44 and the corresponding set function values of input signal 41is less than a preset value.

A relationship between the degree of deviation and the adjustment neededcan be obtained by theoretical calculation, or by an empiricalcorrespondence obtained according to an actual use environment, orthrough a combination thereof.

In some embodiments, through the above setting, input signal 41 finallyarriving at qubit processing unit 42 may satisfy preset parameter values(e.g., including phase, intensity, or frequency, etc.), so that thequbit can be more precisely controlled.

FIG. 5 illustrates a schematic diagram of an example qubit calibrationdevice 500, according to some embodiments of the present disclosure. Insome embodiments, a qubit processing unit 52 and an adjustable device 53are disposed on a single chip 55. Single chip may include a single waferthat is processed to provide qubit processing unit 52 and adjustabledevice 53 (e.g., an adjustable microwave standard responder device 53).In some embodiments, qubit calibration device 500 further includes amode selection device 54. Mode selection device 54 may change a path ofthe input signal 51 via remote controlling (e.g., based on, but notlimited to, electrical signals). If a mode of inputting to qubitprocessing unit 52 is selected, the qubit is controlled. If a mode ofinputting to adjustable device 53 is selected, the step of calibrationmay be performed. In some embodiments, mode selection device 54 isdisposed at a detection signal 56 side.

In some embodiments, qubit processing unit 52 and adjustable device 53are placed as close as possible so that they are placed in the sameenvironment (e.g., within the same temperature range).

In some embodiments, qubit processing unit 52 includes a chip (or a unitmodule on a chip) including one or more qubits. For example, qubitprocessing unit 22 may include: a qubit (e.g., a smallquantum-mechanical system), a resonator, circuitry configured to receivean input signal (e.g., input signal 51, may also be referred to as aqubit control signal), and corresponding circuitry configured to amplifyand output a signal. In some embodiments, adjustable device 53 includesa controllable switch and a plurality of standard devices forcalibration. In some embodiments, the standard devices for calibrationuse standards such as Open\Short\Fixed Load\Thru, and input signal 51may be calibrated based on these different standards.

In some embodiments, input signal 51 is transmitted using a coaxialcable. Input signal 51 may include a signal for controlling a qubit andmay be generated by a control signal generator. For example, the inputsignal 51 may include a microwave signal or a laser signal. Thoseskilled in the art can select any suitable control signal generator andselect parameters, such as phase, intensity, and frequency, of inputsignal 51 according to the desired control over the qubit. The selectedparameters may be simultaneously transmitted to a control device (e.g.,may be control signal generator 105, a module of control signalgenerator 105, or control device 103 communicatively coupled to controlsignal generator 105, FIG. 10 ) for controlling (e.g., adjusting) inputsignal 51 to provide more precise control of the qubit.

In some embodiments, the qubit is based on a superconducting Josephsonjunction.

In some embodiments, single chip 55 is placed in a low-temperatureenvironment in use. The low-temperature environment may include atemperature range from 100 mK to 4.2 K (K refers to Kelvin). Thelow-temperature environment may be provided by, for example, but is notlimited to, a dilution refrigerator. In some embodiments, input signal51 may be distorted when transmitted from a room temperature environment(or a relatively high-temperature region) to the low-temperatureenvironment. For example, the parameters, such as phase, intensity, andfrequency, of input signal 51 may change. As a result, when input signal51 is transmitted to qubit processing unit 52, the actual phase,intensity, frequency and other parameters will deviate from thecorresponding preset values, thereby making the control process over thequbit more difficult, less accurate, or even uncontrollable.

In some embodiments, input signal 51 may be inputted to qubit processingunit 52 to control the qubit or may be inputted to adjustable device 53for calibration. When input signal 51 is inputted to adjustable device53, a detection signal 56 is obtained. Since qubit processing unit 52and adjustable device 53 are placed close to each other (e.g., in thesame environment), input signal 51 arrived at adjustable microwavestandard responder device 53 may be substantially similar or identicalto input signal 51 arrived at qubit processing unit 52.

In some embodiments, detection signal 56 is further fed back to thecontrol device (e.g., to provide information used to control or adjustinput signal 51 transmitted to qubit processing unit 52 on chip 55 formore precise control of qubit) via mode selection device 54. A feedbackpath of detection signal 56 may include transmission “through,” or via“reflection,” or a combination thereof. In some embodiments, the controldevice obtains a degree of deviation between the signal actually arrivedat adjustable device 53 and input signal 51 according to comparisonbetween parameters of detection signal 56 and initial parameters ofinput signal 51. The obtained degree of deviation may be used to makecorresponding adjustment to input signal 51 generated by the controlsignal generator (e.g., control signal generator 105, FIG. 10 ). In someexamples, the adjustment may include adjustment to any one or more ofthe above-mentioned parameters, such as phase, intensity, or frequency.

In some embodiments, the above process may be repeated multiple timesuntil the degree of deviation reaches a preset range of convergence. Insome examples, the preset range of convergence may include that adeviation between any parameter, e.g., phase, intensity, or frequency,of detection signal 56 and the corresponding parameter of input signal51 is less than a preset value. In some other examples, the preset rangeof convergence may include that the deviation of each of phase,intensity, and frequency between detection signal 56 and input signal 51is less than a preset value. In yet some other examples, the presetrange of convergence may include that the deviation between one or moreset function values of phase, intensity, and frequency of detectionsignal 56 and the corresponding set function values of input signal 51is less than a preset value.

A relationship between the degree of deviation and the adjustment neededcan be obtained by theoretical calculation, or by an empiricalcorrespondence obtained according to an actual use environment, orthrough a combination thereof.

In some embodiments, through the above setting, input signal 51 finallyarriving at qubit processing unit 52 may satisfy preset parameter values(e.g., including phase, intensity, or frequency, etc.), so that thequbit can be more precisely controlled.

FIG. 6 illustrates a schematic diagram of an example qubit calibrationdevice 600, according to some embodiments of the present disclosure. Insome embodiments, a qubit processing unit 62 and an adjustable device 63are disposed on a single chip 67. Single chip 67 may include a singlewafer that is processed to provide qubit processing unit 62 andadjustable device 63. In some embodiments, qubit calibration device 600further includes a first mode selection device 61 (e.g., disposed atinput signal side) and a second mode selection device 64 (e.g., disposedat detection signal side). The mode selection device 61 or 64 may changea path of input signal 65 by remote controlling (e.g., based on, but notlimited to, electrical signals). In some examples, if a mode oftransmitting input signal 65 to qubit processing unit 62 is selected,the qubit is controlled. In some other examples, if a mode oftransmitting input signal 65 to adjustable device 63 is selected,calibration (e.g., of input signal 65) may be performed. In someembodiments as shown in FIG. 6 , first mode selection device 61 isdisposed on one side of single chip 67, and second mode selection device64 is disposed on the other side of single chip 67.

In some embodiments, qubit processing unit 62 and adjustable device 63are placed as close as possible so that they are placed in the sameenvironment (e.g., within the same temperature range). In someembodiments, the electrical wires and circuitry connecting first modeselection device 61 and qubit processing unit 62 have substantiallysimilar microwave-responsive characteristics as the electrical wires andcircuitry between first mode selection device 61 and adjustable device63.

In some embodiments, qubit processing unit 62 includes a chip (or a unitmodule on a chip) including one or more qubits. For example, qubitprocessing unit 22 may include: a qubit (e.g., a smallquantum-mechanical system), a resonator, circuitry configured to receivean input signal (e.g., input signal 65, may also be referred to as aqubit control signal), and corresponding circuitry configured to amplifyand output a signal. In some embodiments, adjustable device 63 includesa controllable switch and a plurality of standard devices forcalibration. In some embodiments, the standard devices for calibrationuse standards such as Open\Short\Fixed Load\Thru, and input signal 61may be calibrated based on these different standards.

In some embodiments, input signal 65 is transmitted using a coaxialcable. Input signal 65 may include a signal for controlling a qubit andmay be generated by a control signal generator. For example, inputsignal 65 may include a microwave signal or a laser signal. Thoseskilled in the art can select any suitable signal generator and selectparameters, such as phase, intensity, and frequency, of input signal 65according to the desired control over the qubit. The selected parametersmay be simultaneously transmitted to a control device (e.g., controlsignal generator 105, a module of control signal generator 105, orcontrol device 103 communicatively coupled to control signal generator105, FIG. 10 ) for controlling (e.g., adjusting) input signal 65 toprovide more precise control of the qubit.

In some embodiments, the qubit is based on a superconducting Josephsonjunction.

In some embodiments, single chip 67 is placed in a low-temperatureenvironment in use. The low-temperature environment may include atemperature range from 100 mK to 4.2 K (K refers to Kelvin). Thelow-temperature environment may be provided by, for example, but is notlimited to, a dilution refrigerator. In some embodiments, input signal65 may be distorted when transmitted from a room temperature environment(or a relatively high-temperature region) to the low-temperatureenvironment. For example, the parameters, such as phase, intensity, andfrequency, of input signal 65 may change. As a result, when input signal65 is transmitted to qubit processing unit 62, the actual phase,intensity, frequency and other parameters will deviate from thecorresponding preset values, thereby making the control process over thequbit more difficult, less accurate, or even uncontrollable.

In some embodiments, input signal 65 may be inputted to qubit processingunit 62 via first mode selection device 61 to control the qubit or maybe inputted to adjustable device 63 for calibration. When input signal65 is inputted to adjustable device 63, detection signal 66 is obtained.Since qubit processing unit 62 and adjustable device 63 are placed closeto each other (e.g., in the same environment), input signal 65 arrivedat adjustable device 63 may be substantially similar or identical toinput signal 65 arrived at qubit processing unit 62.

In some embodiments, detection signal 66 is further fed back to thecontrol device (e.g., to provide information used to control or adjustinput signal 65 transmitted to qubit processing unit 62 on chip 67 formore precise control of qubit) via second mode selection device 64. Afeedback path of detection signal 66 may include transmission “through,”or via “reflection,” or a combination thereof. In some embodiments, thecontrol device obtains a degree of deviation between the signal actuallyarrived at adjustable device 63 and input signal 65 according tocomparison between parameters of detection signal 66 and initialparameters of input signal 65. The obtained degree of deviation may beused to make corresponding adjustment to input signal 65 generated bythe control signal generator (e.g., control signal generator 105, FIG.10 ). In some examples, the adjustment may include adjustment to any oneor more of the above-mentioned parameters, such as phase, intensity, orfrequency.

In some embodiments, the above process may be repeated multiple timesuntil the degree of deviation reaches a preset range of convergence. Insome examples, the preset range of convergence may include that adeviation between any parameter, e.g., phase, intensity, or frequency,of detection signal 66 and the corresponding parameter of input signal65 is less than a preset value. In some other examples, the preset rangeof convergence may include that the deviation of each of phase,intensity, and frequency between detection signal 66 and input signal 65is less than a preset value. In yet some other examples, the presetrange of convergence may include that the deviation between one or moreset function values of phase, intensity, and frequency of detectionsignal 66 and the corresponding set function values of input signal 65is less than a preset value.

A relationship between the degree of deviation and the adjustment neededcan be obtained by theoretical calculation, or by an empiricalcorrespondence obtained according to an actual use environment, orthrough a combination thereof.

In some embodiments, through the above setting, input signal 65 finallyarriving at qubit processing unit 62 may satisfy preset parameter values(e.g., including phase, intensity, or frequency, etc.), so that thequbit can be more precisely controlled.

FIG. 7 illustrates a schematic diagram of an example qubit calibrationdevice 700, according to some embodiments of the present disclosure. Insome embodiments, a qubit processing unit 72 and an adjustable device 73are disposed on a single PCB 77. Qubit calibration device 700 mayfurther include a first mode selection device 71 and a second modeselection device 74. The mode selection device 71 or 74 may change apath of input signal 75 by remote controlling (e.g., based on, but notlimited to, electrical signals). In some examples, if a mode oftransmitting input signal 75 to qubit processing unit 72 is selected,the qubit is controlled. In some other examples, if a mode oftransmitting input signal 75 to adjustable device 73 is selected,calibration (e.g., of input signal 75) may be performed. In someembodiments as shown in FIG. 7 , first mode selection device 71 isdisposed on one side of a single circuit board 77 (e.g., prior to inputsignal 75 entering PCB 77), and second mode selection device 74 isdisposed on the other side of a single circuit board 77 (e.g., afterobtaining detection signal 76 from PCB 77).

In some embodiments, qubit processing unit 72 and adjustable device 73are placed as close as possible so that they are placed in the sameenvironment (e.g., within the same temperature range). In someembodiments, the electrical wires and circuitry connecting first modeselection device 71 and qubit processing unit 72 have substantiallysimilar microwave-responsive characteristics as the electrical wires andcircuitry between first mode selection device 71 and adjustable device73.

In some embodiments, qubit processing unit 72 includes a chip (or a unitmodule on a chip) including one or more qubits. For example, qubitprocessing unit 72 may include: a qubit (e.g., a smallquantum-mechanical system), a resonator, circuitry configured to receivean input signal (e.g., input signal 75, may also be referred to as aqubit control signal), and corresponding circuitry configured to amplifyand output a signal. In some embodiments, adjustable device 73 includesa controllable switch and a plurality of standard devices forcalibration. In some embodiments, the standard devices for calibrationuse standards such as Open\Short\Fixed Load\Thru, and input signal 21may be calibrated based on these different standards.

In some embodiments, input signal 75 is transmitted using a coaxialcable. Input signal 75 may include a signal for controlling a qubit andmay be generated by a control signal generator. For example, inputsignal 75 may include a microwave signal or a laser signal. Thoseskilled in the art can select any suitable signal generator and selectparameters, such as phase, intensity, and frequency, of input signal 75according to the desired control over the qubit. The selected parametersmay be simultaneously transmitted to a control device (e.g., controlsignal generator 105, a module of control signal generator 105, orcontrol device 103 communicatively coupled to control signal generator105, FIG. 10 ) for controlling (e.g., adjusting) input signal 75 toprovide more precise control of the qubit.

In some embodiments, the qubit is based on a superconducting Josephsonjunction.

In some embodiments, PCB 77 is placed in a low-temperature environmentin use. The low-temperature environment may include a temperature rangefrom 100 mK to 4.2 K (K refers to Kelvin). The low-temperatureenvironment may be provided by, for example, but is not limited to, adilution refrigerator. In some embodiments, input signal 75 may bedistorted when transmitted from a room temperature environment (or arelatively high-temperature region) to the low-temperature environment.For example, the parameters, such as phase, intensity, and frequency, ofinput signal 75, may change. As a result, when input signal 75 istransmitted to qubit processing unit 72, the actual phase, intensity,frequency and other parameters will deviate from the correspondingpreset values, thereby making the control process over the qubit moredifficult, less accurate, or even uncontrollable.

In some embodiments, input signal 75 may be inputted to qubit processingunit 72 via first mode selection device 71 to control the qubit or maybe inputted to adjustable device 73 for calibration. When input signal75 is inputted to adjustable device 73, detection signal 76 is obtained.Since qubit processing unit 72 and adjustable device 73 are placed closeto each other (e.g., in the same environment), input signal 75 arrivedat adjustable device 73 may be substantially similar or identical toinput signal 75 arrived at qubit processing unit 72.

In some embodiments, detection signal 76 is further fed back to thecontrol device (e.g., to provide information used to control or adjustinput signal 75 transmitted to qubit processing unit 72 on PCB 77 formore precise control of qubit) via second mode selection device 74. Afeedback path of detection signal 76 may include transmission “through,”or via “reflection,” or a combination thereof. In some embodiments, thecontrol device obtains a degree of deviation between the signal actuallyarrived at adjustable device 73 and input signal 75 according tocomparison between parameters of detection signal 76 and initialparameters of input signal 75. The obtained degree of deviation may beused to make corresponding adjustment to input signal 75 generated bythe control signal generator (e.g., control signal generator 105, FIG.10 ). In some examples, the adjustment may include adjustment to any oneor more of the above-mentioned parameters, such as phase, intensity, orfrequency.

In some embodiments, the above process may be repeated multiple timesuntil the degree of deviation reaches a preset range of convergence. Insome examples, the preset range of convergence may include that adeviation between any parameter, e.g., phase, intensity, or frequency,of detection signal 76 and the corresponding parameter of input signal75 is less than a preset value. In some other examples, the preset rangeof convergence may include that the deviation of each of phase,intensity, and frequency between detection signal 76 and input signal 75is less than a preset value. In yet some other examples, the presetrange of convergence may include that the deviation between one or moreset function values of phase, intensity, and frequency of detectionsignal 76 and the corresponding set function values of input signal 75is less than a preset value.

A relationship between the degree of deviation and the adjustment neededcan be obtained by theoretical calculation, or by an empiricalcorrespondence obtained according to an actual use environment, orthrough a combination thereof.

In some embodiments, through the above setting, input signal 75 finallyarriving at qubit processing unit 72 may satisfy preset parameter values(e.g., including phase, intensity, or frequency, etc.), so that thequbit can be more precisely controlled.

FIG. 8 illustrates a schematic diagram of an example qubit calibrationdevice 800, according to some embodiments of the present disclosure. Insome embodiments, a qubit processing unit 82 and an adjustable device 83are disposed on a single chip 87. Single chip 87 may include a singlewafer that is processed to provide qubit processing unit 82 andadjustable device 83. Qubit calibration device 800 may further include afirst mode selection device 81 and a second mode selection device 84.The mode selection device 81 or 84 may change a path of input signal 85by remote controlling (e.g., based on, but not limited to, electricalsignals). In some examples, if a mode of transmitting input signal 85 toqubit processing unit 82 is selected, the qubit is controlled. In someother examples, if a mode of transmitting input signal 85 to adjustabledevice 83 is selected, calibration (e.g., of input signal 85) may beperformed. In some embodiments, first mode selection device 81 andsecond mode selection device 84 are disposed on the same chip 87 asqubit processing unit 82 and adjustable device 83 as shown in FIG. 8 .Further, first mode selection device 81 is disposed on one side of qubitprocessing unit 82 and adjustable device 83 (e.g., prior to input signal85 entering qubit processing unit 82 or adjustable device 83), andsecond mode selection device 84 is disposed on the other side of qubitprocessing unit 82 and adjustable device 83 (e.g., after obtaining adetection signal 86 from adjustable device 83).

In some embodiments, qubit processing unit 82 and adjustable device 83are placed as close as possible so that they are placed in the sameenvironment (e.g., within the same temperature range). In someembodiments, the electrical wires and circuitry connecting first modeselection device 81 and qubit processing unit 82 have substantiallysimilar microwave-responsive characteristics as the electrical wires andcircuitry between first mode selection device 81 and adjustable device83.

In some embodiments, qubit processing unit 82 includes a chip (or a unitmodule on a chip) including one or more qubits. For example, qubitprocessing unit 82 may include: a qubit (e.g., a smallquantum-mechanical system), a resonator, circuitry configured to receivean input signal (e.g., input signal 85, may also be referred to as aqubit control signal), and corresponding circuitry configured to amplifyand output a signal. In some embodiments, adjustable device 83 includesa controllable switch and a plurality of standard devices forcalibration. In some embodiments, the standard devices for calibrationuse standards such as Open\Short\Fixed Load\Thru, and input signal 21may be calibrated based on these different standards.

In some embodiments, input signal 85 is transmitted using a coaxialcable. Input signal 85 may include a signal for controlling a qubit andmay be generated by a control signal generator. For example, inputsignal 85 may include a microwave signal or a laser signal. Thoseskilled in the art can select any suitable signal generator and selectparameters, such as phase, intensity, and frequency, of input signal 85according to the desired control over the qubit. The selected parametersmay be simultaneously transmitted to a control device (e.g., controlsignal generator 105, a module of control signal generator 105, orcontrol device 103 communicatively coupled to control signal generator105, FIG. 10 ) for controlling (e.g., adjusting) input signal 85 toprovide more precise control of the qubit.

In some embodiments, the qubit is based on a superconducting Josephsonjunction.

In some embodiments, single chip 87 is placed in a low-temperatureenvironment in use. The low-temperature environment may include atemperature range from 100 mK to 4.2 K (K refers to Kelvin). Thelow-temperature environment may be provided by, for example, but is notlimited to, a dilution refrigerator. In some embodiments, input signal85 may be distorted when transmitted from a room temperature environment(or a relatively high-temperature region) to the low-temperatureenvironment. For example, the parameters, such as phase, intensity, andfrequency, of input signal 85, may change. As a result, when inputsignal 85 is transmitted to qubit processing unit 82, the actual phase,intensity, frequency and other parameters will deviate from thecorresponding preset values, thereby making the control process over thequbit more difficult, less accurate, or even uncontrollable.

In some embodiments, input signal 85 may be inputted to qubit processingunit 82 via first mode selection device 81 to control the qubit or maybe inputted to adjustable device 83 for calibration. When input signal81 is inputted to adjustable device 83, detection signal 86 is obtained.Since qubit processing unit 82 and adjustable device 83 are placed closeto each other (e.g., in the same environment), input signal 85 arrivedat adjustable device 83 may be substantially similar or identical toinput signal 85 arrived at qubit processing unit 82.

In some embodiments, detection signal 86 is further fed back to thecontrol device (e.g., to provide information used to control or adjustinput signal 85 transmitted to qubit processing unit 82 on chip 87 formore precise control of qubit) via second mode selection device 84. Afeedback path of detection signal 86 may include transmission “through,”or via “reflection,” or a combination thereof. In some embodiments, thecontrol device obtains a degree of deviation between the signal actuallyarrived at adjustable device 83 and input signal 85 according tocomparison between parameters of detection signal 86 and initialparameters of input signal 85. The obtained degree of deviation may beused to make corresponding adjustment to input signal 85 generated bythe control signal generator (e.g., control signal generator 105, FIG.10 ). In some examples, the adjustment may include adjustment to any oneor more of the above-mentioned parameters, such as phase, intensity, orfrequency.

In some embodiments, the above process may be repeated multiple timesuntil the degree of deviation reaches a preset range of convergence. Insome examples, the preset range of convergence may include thatdeviation between any parameter, e.g., phase, intensity, or frequency,of detection signal 86 and the corresponding parameter of input signal85 is less than a preset value. In some other examples, the preset rangeof convergence may include that the deviation of each of phase,intensity, and frequency between detection signal 86 and input signal 85is less than a preset value. In yet some other examples, the presetrange of convergence may include that the deviation between one or moreset function values of phase, intensity, and frequency of detectionsignal 86 and the corresponding set function values of input signal 85is less than a preset value.

A relationship between the degree of deviation and the adjustment neededcan be obtained by theoretical calculation, or by an empiricalcorrespondence obtained according to an actual use environment, orthrough a combination thereof.

In some embodiments, through the above setting, input signal 85 finallyarriving at qubit processing unit 82 may satisfy preset parameter values(e.g., including phase, intensity, or frequency, etc.), so that thequbit can be more precisely controlled.

FIG. 9 illustrates a schematic diagram of an example qubit calibrationdevice 900, according to some embodiments of the present disclosure. Insome embodiments, a qubit processing unit 92 and an adjustable device 93are disposed on a single PCB 97. Qubit calibration device 900 mayfurther include a first mode selection device 91 and a second modeselection device 94. The mode selection device 91 or 94 may change apath of input signal 95 by remote controlling (e.g., based on, but notlimited to, electrical signals). In some examples, if a mode oftransmitting input signal 95 to qubit processing unit 92 is selected,the qubit is controlled. In some other examples, if a mode oftransmitting input signal 95 to adjustable device 93 is selected,calibration (e.g., of input signal 95) may be performed. In someembodiments, first mode selection device 91 and second mode selectiondevice 94 are disposed on the same PCB 97 as qubit processing unit 92and adjustable device 93 as shown in FIG. 9 . Further, first modeselection device 91 is disposed on one side of qubit processing unit 92and adjustable device 93 (e.g., prior to input signal 95 entering qubitprocessing unit 92 or adjustable device 93), and second mode selectiondevice 94 is disposed on the other side of qubit processing unit 92 andadjustable device 93 (e.g., after obtaining a detection signal 96 fromadjustable device 93).

In some embodiments, qubit processing unit 92 and the adjustable device93 are placed as close as possible so that they are placed in the sameenvironment (e.g., within the same temperature range). In someembodiments, the electrical wires and circuitry connecting first modeselection device 91 and qubit processing unit 92 have substantiallysimilar microwave-responsive characteristics as the electrical wires andcircuitry between first mode selection device 91 and adjustable device93.

In some embodiments, qubit processing unit 92 includes a chip (or a unitmodule on a chip) including one or more qubits. For example, qubitprocessing unit 82 may include: a qubit (e.g., a smallquantum-mechanical system), a resonator, circuitry configured to receivean input signal (e.g., input signal 95, may also be referred to as aqubit control signal), and corresponding circuitry configured to amplifyand output a signal. In some embodiments, adjustable device 93 includesa controllable switch and a plurality of standard devices forcalibration. In some embodiments, the standard devices for calibrationuse standards such as Open\Short\Fixed Load\Thru, and input signal 21may be calibrated based on these different standards.

In some embodiments, input signal 95 is transmitted using a coaxialcable. Input signal 95 may include a signal for controlling a qubit andmay be generated by a control signal generator. For example, inputsignal 95 may include a microwave signal or a laser signal. Thoseskilled in the art can select any suitable signal generator and selectparameters, such as phase, intensity, and frequency, of input signal 95according to the desired control over the qubit. The selected parametersmay be simultaneously transmitted to a control device (e.g., controlsignal generator 105, a module of control signal generator 105, orcontrol device 103 communicatively coupled to control signal generator105, FIG. 10 ) for controlling (e.g., adjusting) input signal 95 toprovide more precise control of the qubit.

In some embodiments, the qubit is based on a superconducting Josephsonjunction.

In some embodiments, PCB 97 is placed in a low-temperature environmentin use.

The low-temperature environment may include a temperature range from 100mK to 4.2 K (K refers to Kelvin). The low-temperature environment may beprovided by, for example, but is not limited to, a dilutionrefrigerator. In some embodiments, input signal 95 may be distorted whentransmitted from a room temperature environment (or a relativelyhigh-temperature region) to the low-temperature environment. Forexample, the parameters such as phase, intensity, and frequency, ofinput signal 95, may change. As a result, when input signal 95 istransmitted to qubit processing unit 92, the actual phase, intensity,frequency and other parameters will deviate from the correspondingpreset values, thereby making the control process over the qubit moredifficult, less accurate, or even uncontrollable.

In some embodiments, input signal 95 may be inputted to qubit processingunit 92 via first mode selection device 91 to control the qubit or maybe inputted to adjustable device 93 for calibration. When input signal91 is inputted to adjustable device 93, detection signal 96 is obtained.Since qubit processing unit 92 and adjustable device 93 are placed closeto each other (e.g., in the same environment), input signal 95 arrivedat adjustable device 93 may be substantially similar or identical toinput signal 95 arrived at qubit processing unit 92.

In some embodiments, detection signal 96 is further fed back to thecontrol device (e.g., to provide information used to control or adjustinput signal 95 transmitted to qubit processing unit 92 on PCB 97 formore precise control of qubit) the second mode selection device 94. Afeedback path of detection signal 96 may include transmission “through,”or via “reflection,” or a combination thereof. In some embodiments, thecontrol device obtains a degree of deviation between the signal actuallyarrived at adjustable device 93 and input signal 95 according torelevant parameters of detection signal 96 and initial parameters ofinput signal 95. The obtained degree of deviation may be used to makecorresponding adjustment to input signal 95 generated by the controlsignal generator (e.g., control signal generator 105, FIG. 10 ). In someexamples, the adjustment may include adjustment to any one or more ofthe above-mentioned parameters, such as phase, intensity, or frequency.

In some embodiments, the above process may be repeated multiple timesuntil the degree of deviation reaches a preset range of convergence. Insome examples, the preset range of convergence may include thatdeviation between any parameter, e.g., phase, intensity, or frequency,of detection signal 96 and the corresponding parameter of input signal95 is less than a preset value. In some other examples, the preset rangeof convergence may include that the deviation of each of phase,intensity, and frequency between detection signal 96 and input signal 95is less than a preset value. In yet some other examples, the presetrange of convergence may include that the deviation between one or moreset function values of phase, intensity and frequency of detectionsignal 96 and the corresponding set function values of input signal 95is less than a preset value.

A relationship between the degree of deviation and the adjustment neededcan be obtained by theoretical calculation, or by an empiricalcorrespondence obtained according to an actual use environment, orthrough a combination thereof.

In some embodiments, through the above setting, input signal 95 finallyarrived at qubit processing unit 92 may satisfy preset parameter values(e.g., including phase, intensity, or frequency, etc.), so that thequbit can be more precisely controlled.

FIG. 10 illustrates a schematic diagram of an example qubit measurementand control system 1000, according to some embodiments of the presentdisclosure. In some embodiments, environment 101 is a low-temperatureenvironment as discussed above. Device 102 may include a qubitcalibration device (e.g., qubit calibration device 200, 300, 400, 500,600, 700, 800, or 900) as discussed in the above embodiments. Forexample, device 102 includes qubit processing unit 1021 (e.g., qubitprocessing unit 22, 32, 42, 52, 62, 72, 82, or 92 as discussed above)and adjustable device 1022 (e.g., adjustable device 23, 33, 43, 53, 63,73, 83, or 93 as discussed above).

In some embodiments as shown in FIG. 10 , qubit measurement and controlsystem 1000 further includes a control device 103, a control signalgenerator 105 (e.g., for generating input signal 111, and for measuringor evaluating detection signal 110) coupled to device 102, and anoptional computer 104. In some embodiments, control device 103 may alsoinclude a computer. In some embodiments, control device 103, computer104, and control signal generator 105 are communicatively connected toeach other. Detection signal 110 may be transmitted to control signalgenerator 105 first, and then processed by control device 103 andcomputer 104. Control device 103 may be used to control an automaticcalibration system. Some embodiments of the processes of signalgeneration and calibration are as described above in the presentdisclosure.

In some embodiments, input signal 111 generated by control signalgenerator 105 is transmitted to device 102 placed in low-temperatureenvironment 101. Input signal 111 may be transmitted to qubit processingunit 1021 for qubit processing or to adjustable device 1022 for qubitcalibration. A feedback signal (e.g., detection signal 110 as discussedin the present disclosure) obtained from device 102 may be fed back tocontrol signal generator 105. Control signal generator 105 (or controldevice 103 coupled to control signal generator 105) may comparedetection signal 110 with input signal 111 (e.g., generated by controlsignal generator 105 and prior to being transmitted to qubit calibrationdevice 102). For example, differences of one or more parameters (e.g.,phase, intensity, or frequency as discussed above) between the detectionsignal 110 and input signal 111 are determined, so as to understand thesignal distortion caused by the temperature change from a roomtemperature environment (e.g., at control signal generator 105) tolow-temperature environment 101 (e.g., at device 102). In someembodiments, based on the parameter deviation caused by the signaldistortion, control signal generator 105 may adjust one or moreparameters of the generated input signal 111, so as to feed desiredinput signal 111 into device 102 for qubit control with improvedprecision.

FIG. 11 illustrates a flowchart of an example qubit measurement andcontrol method, according to some embodiments of the present disclosure.The method includes: receiving a qubit control signal at a calibrationdevice (e.g., an adjustable device 1022, FIG. 10 ) corresponding(adjacent) to a qubit; detecting the qubit control signal to obtain adetection signal; and adjusting (e.g., via control signal generator 105,or control device 103 coupled to control signal generator 105, FIG. 10), at least based on a comparison between the detection signal and thequbit control signal, the control signal for controlling the qubit, sothat the control signal transmitted to a qubit can be more accuratelycontrollable.

As used herein, unless specifically stated otherwise, the term “or”encompasses all possible combinations, except where infeasible. Forexample, if it is stated that a database may include A or B, then,unless specifically stated otherwise or infeasible, the database mayinclude A, or B, or A and B. As a second example, if it is stated that adatabase may include A, B, or C, then, unless specifically statedotherwise or infeasible, the database may include A, or B, or C, or Aand B, or A and C, or B and C, or A and B and C.

It is to be understood that the above description is intended to beillustrative and not restrictive. For example, the embodiments (oraspects thereof) described above may be used in conjunction with eachother. In addition, many modifications may be made to adapt a particularsituation or content to the teachings of some embodiments withoutdeparting from the scope of the embodiments. While the dimensions andtypes of materials described herein are intended to define parameters ofsome embodiments, the embodiments are by no means restrictive, butrather illustrative embodiments. Many other embodiments will be apparentto those skilled in the art upon review of the description. The scope ofsome embodiments should be determined by reference to the appendedclaims and the full scope of equivalents covered by such claims. In theappended claims, the terms “include” and “wherein” are used as readablelanguage equivalents of the corresponding terms “comprise” and “where.”In addition, in the appended claims, the terms “first,” “second,”“third,” etc. are used merely as labels, and they are not intended toimpose numerical requirements on their objects. In addition, thelimitations of the appended claims are not to be written in a format ofmeans and functions.

It should be also explained that terms “include,” “comprise” or anyother variations thereof are intended to contain non-exclusiveinclusion, so that processes, methods, goods or equipment including aseries of factors not only include the factors, but also include otherfactors which are not clearly listed, or also include inherent factorsof the processes, methods, goods or equipment. The factors restrained bya statement “include a . . . ” shall not exclude that other same factorsalso exist in the processes, methods, goods or equipment including thefactors under the condition that no more restraints are required.

Those skilled in the art should understand that some embodiments of thedisclosure may be provided as a method, equipment or a computer programproduct. Thus, a form of complete hardware embodiment, a form ofcomplete software embodiment or a form of embodiment integratingsoftware and hardware may be adopted in the disclosure. Moreover, a formof computer program product implemented on one or more computeravailable storage media (including, but not limited to, a disk memory, aCD-ROM, an optical memory and the like) containing computer availableprogram codes may be adopted in the disclosure.

The computer readable media comprise non-volatile and volatile,removable and non-removable media. Information can be saved in any wayor by any technology. Information can be computer readable instructions,data structures, program modules or other data. Examples of the storagemedia of the computer comprise but are not limited to phase-changerandom access memory (PRAM), static random access memory (SRAM), dynamicrandom access memory (DRAM), other types of random access memories(RAM), read-only memory (ROM), electrically erasable programmableread-only memory (EEPROM), flash memory or other memory technologies,compact disk-read only memory (CD-ROM), digital versatile disc (DVD) orother optical memories, cassette tape, tape and disk memory or othermagnetic memories or any other non-transport media. The storage mediacan be used for saving the information which a computing device canaccess. According to the definition herein, the computer readable mediumdoes not comprise computer readable transitory media, such as modulateddata signals and carrier waves.

The written description uses examples to disclose some embodiments,including an optimal mode, and also to enable those skilled in the artto practice some embodiments, including making and using any device orsystem, and performing any combination method. The scope of protectionof some embodiments is defined by the claims, and may include otherexamples that are apparent to those skilled in the art. If such otherexamples have structural elements that are not different from theliteral language of the claims, or if they include equivalent structuralelements that are not substantially different from the literal languageof the claims, they are intended to be within the scope of the claims.

1. A qubit calibration device, comprising: a qubit processing unitincluding circuitry configured to, after receiving a qubit controlsignal, process one or more qubits; and an adjustable device configuredto, after receiving the qubit control signal, generate a detectionsignal used to further adjust the qubit control signal, wherein thequbit processing unit and the adjustable device are disposed on a samesubstrate.
 2. The qubit calibration device according to claim 1, whereinthe one or more qubits are based on a superconducting Josephsonjunction.
 3. The qubit calibration device according to claim 1, furthercomprising: a first mode selection device located on one side of thequbit processing unit and disposed on the same substrate.
 4. The qubitcalibration device according to claim 3, further comprising: a secondmode selection device located on the other side of the qubit processingunit from the first mode selection device, and the second mode selectiondevice being disposed on the same substrate.
 5. The qubit calibrationdevice according to claim 1, wherein the qubit control signal comprisesa microwave signal or a laser signal.
 6. The qubit calibration deviceaccording to claim 1, wherein the qubit control signal is adjusted by atleast one of the parameters including phase, intensity, and frequency.7. The qubit calibration device according to claim 1, wherein thesubstrate is disposed in a low-temperature environment comprising aliquid helium temperature zone.
 8. The qubit calibration deviceaccording to claim 1, wherein the substrate is a single chip or aprinted circuit board (PCB).
 9. A qubit measurement and control method,comprising: receiving a qubit control signal at an adjustable device;detecting, by the adjustable device, the qubit control signal to obtaina detection signal, wherein the qubit control signal is adjusted basedon a comparison between the detection signal and the qubit controlsignal.
 10. The qubit measurement and control method according to claim9, wherein the qubit control signal comprises a microwave signal or alaser signal.
 11. The qubit measurement and control method according toclaim 9, wherein the qubit control signal is adjusted by at least one ofthe following parameters: phase, intensity, and frequency.
 12. The qubitmeasurement and control method according to claim 9, wherein thedetection signal is transmitted to a control device via a reflectionmode or a through mode.